Birds, which are to be paired for the first time, should be previously placed in the same cage for seven or eight days, in order to become acquainted and accustomed to live together. If two females are to be caged with one male, it is especially necessary that they should be together long enough to leave off quarrelling, and the pairing cage should be divided into two equal parts, communicating by a sliding door. This being done, a lively male and one of the females should be placed in the first division; as soon as she has laid, the male should be moved into the other division, the door of separation being shut; but as soon as the other has also laid, the door may be left open: the male will then visit the females alternately, and they will not trouble themselves about each other; but without these precautions jealousy would incline them to fight, and destroy each other's eggs. When it is intended to place a great many females, double or treble the number of males, in a room or aviary, the latter should always be first paired with a single female, which will ever after remain the favourite; and it will only be when she is about to sit that he will pair with the others, and this is all the notice he will take of them, for afterwards he will only notice their young. It is from these mothers, however, that the most and the best birds are generally procured.
If the floor of the room or aviary is well covered with moss, little else need be added for making the nests, otherwise they should be supplied with the hair of cows and deer, hogs' bristles, fine hay, lint, wool cut two or three inches long, paper shavings, and the like. That which is coarsest serves for the outside, and the softest and finest for the inside. If they have shrubs, traces of the natural instinct of the canary are soon observed in the nests which they construct without the help of the turner or basket weaver; but they are of an inelegant form, and the outside is not very carefully finished. The females alone, as is usual among birds, are the builders, the males only choosing the situation and bringing the materials. It is in the nest, where the female is in continual motion, that the pairing takes place; she invites the male by constant little chirpings, repeated more quickly the nearer she is to laying. Seven or eight days are generally reckoned from the first pairing to the laying of the first egg; the other eggs, whose number varies, without exceeding six, are laid successively every following day, and often at the same hour. The laying ended, pairing continues during the first days of incubation.